Before Nissan Skylines were imported by dedicated enthusiasts into their home countries, Skylines were an unheard of car outside of Japan, and to the few foreigners who had heard of it, it had an almost mythical status. Japan then was known only for small and cheap commuter cars which were good for only one thing - sipping fuel. But the first gas crisis had already hit and the world as a whole had woken up to the fact that oil was a finite resource and an oil cartel could and did control the price.
But a few decades later, Skylines have become synonymous with blazing performance comparable to German or Italian sports cars, and they can now be found in every corner of the world. As a result, a lot of previous owners now sell a used Nissan Skyline GTR. Selling a Skyline is practically the same as selling most other cars but with a few notable differences. First of all, buyers of these types of cars are usually knowledgeable about cars. So if you intend to sell a used Nissan Skyline GTR, make sure that the car is in good shape. Aside from making the car look as fresh as you can make it, take a look at possible mechanical and electronics issues that a buyer may bring up. Conscientious buyers will have done their research about how much a particular model should sell for and what maintenance issues and costs are involved with a certain variant.
Secondly, Nissan Skylines are not exactly daily drivers, nor are they family cars. Their reason for being is to go fast, very fast, with little consideration for backseat passengers, fuel economy or cost of maintenance. Consequently, the market for such a car is limited, compared to commuter cars which even enthusiasts buy for their daily driving needs. People who sell a used Nissan Skyline GTR are also well aware that at the market prices these cars command, there are already plenty of viable alternatives for car guys looking for their performance fix.